The magnetically mesoporous SiO2@Fe3O4 nanocomposites were synthesized by sol-gel method and extracted by ethanol solution. The support was characterized by high resolution transmission electron microscopy (HRTEM), N2 adsorption-desorption isotherms and vibration sample magnetometer (VSM). A long carbon chain Oxime Carbapalladacycle complex was grafted onto this support and the effect of the catalyst was investigated for the Heck reaction of aryl halides with olefins. The results demonstrated that the support with diameter 150 nm was superparamagnetic characteristics (saturation magnetization was 8.78 emu/g) and the thus recycled catalyst could be reused for 6 times with significant loss of activity in the coupling-reaction of iodobenzene and ethyl acrylate. In addition, the catalyst could be simply recycled with the assistance of an external magnet.